Process for working guide sleeves for spring rings



y 3, 1932- B. FOERSTER I 1,856,952

PROCESS FOR WORKING GUIDE SLEEVES FOR SPRING RINGS Filed Jan. 20, 1931 2 Sheets-Sheet l y 3, 1932- B. FOERSTER 1,856,952

PROCESS FOR WORKING GUIDE SLEEVES FOR SPRING RINGS Filed Jan. 20, 1931 2 Sheets-Sheet 2 Patented May 3, 1932 UNITED STATES BEBNHARD FOERSTER, OF PFORZHEIM, GERMANY PROCESS FOR WORKING GUIDE SLEEVES FOR SPRING-"RINGS Application filed January 20, 1931, Serial No. 509,966, and in Germany October 14, 1929.

This invention relates to a process for working guide sleeves for spring rings.

As is known spring rings are used as fastening means for ornamental chains of all kinds and also as connecting means for Watch-key and similar chains. They consistessentially of three parts, namely the sleeve, bent ringshape, the catch guided in this sleeve, and the catch spring pressing the catch continually into its locking position.

Spring rings are known with slotted or unslotted guide sleeves. The longitudinal slot provided in the slotted guide sleeves serves for guiding the shank of the catch button projecting through the slot on which the catch made of wire can be displaced against the action of the catch spring so that the ring gap in the sleeve bridged by the spring actuated catch opens.

In the mass production of a small object such as the guide sleeve, special diiiiculties are encountered in making a clean usable longitudinal slot. This should aiford agood smooth guiding with suitable stop ends for the shank of the catch to be easily inserted in the guide sleeve. For this purpose it is essential that all kinds of burr are removed without expensive subsequent manual labor and further that the slot is of suitable form for inserting the catch spring and the catch.

This invention solves this problem in a very satisfactory manner, both from a technical as also from an economical point of view.

The new process consists in that the longitudinal slot of the guide sleeve is cut by a milling cutter, saw or the like and then finished by means of a like or similar tool the cutting edge of which is however moved in the opposite direction, that moreover the cutting surface visible from the outer side, produced by the cutting of the slot, and the burr-like edge existing on the edge of this latter are removed by means of tapered end mills, and at the same time a funnel-shaped insertion opening is produced for the catch spring and the catch.

The process is hereinafter described with reference to the accompanying drawings, in which:

Fig. 1 is a front elevation of a periodically rotated revolving disc onto which the sleeves are deposited for working.

Fig. 2 is a top plan view of the revolving disc and of the working toolsarranged on its circumference. '55

Figs. 3, fl; and'5 are each a top plan view of the first, second, third and fifth working point.

Fig. 6 is a top plan View partly in section of a spring sleeve ready for the introduction cc of the catch spring and of the catch pin.

Fig. 7 shows in front view the slot after the first and secon'doperations.

Fig. 8 shows in front view the-finished widened slot.

To bring the guide sleeves'z' to the first working point, that is in the example shown to the milling cutter p, they are each placed by hand or with the aid of -a special feeding and depositing device in a ring-shaped .de- 7 pression m of a revolving disc n which is intermittently rotated in known manner. Byfmeans of this disc the blanks are fed to the difierent working points. The guide sleeves i are deposited in such a manner that in all blanks theslot i is situated-at the proper position, that isv shortly behind the gap in the sleeves. I-n'order to preventthe blank 2' from changing its position in relation to the revolving disc a during the work-' so ing, small retaining pins n fitting exactly in the gaps of the sleeves, are provided in guide the depressions Moreover the blanks i revolving disc at, and exposing, also in a similar manner to the, revolving disc 'n,fso much surface of theblank z as is necessary for the unimpeded working thereof.

In the first working positionshown-on an "enlarged scalefin F ig..3 .theguide slotc' (Fig. 16) forthe shankof thespringlknobis milled.

This is effected by;means o-fadisc cutter p which rotatesfor example'in-the direction B. Experience has shown-that when milling the slot 2' a burr i always remains extending from end to end of the slot. Hitherto the removal of this burr has been laboriously effected by hand.

At the second working point shown on an enlarged scale in Fig. 4 a second disc cutter g engages in the slot 2' provided with the burr i This cutter rotates in the direction D, which is opposite to the direction B. It has been found that the slot burr '1 which hitherto yielded to the cutter p and remained adhering to the edge of the slot, isbroken u and completely removed.

Owing to the milling of the slot 2' with the cutters p and g sloping cut faces 2' visible from the outer side (Figs. 4 and 7 are produced at the ends of the slots, which faces impede the insertion both of the catch spring and also of the catch proper, as their inner edges are of burr-like sharpness. Moreover these sloping faces 2' do not afford a good, close fitting abutment for the shank of the catch knob. These sloping faces are removed at the third and fifth working points, shown combined and on a larger scale in Fig. 5, by means of the tapered milling cutters 1" and s so that the insertion opening for the clip spring and the clip, formed by the slot 2', is atthe same time widened in funnel-shape corresponding to the shape of the tapered end mills. Owing to this shaping of the slot the finished, inserted catch slides easily without hindrance.

The slot i is in itself too narrow for inserting the spring and catch. 7 It is widened at the fourth working point by means of a tapered ram a, Fig. 2, so that it receives the shape shown in Fig. 8.

At the last working point the finished worked blank 1' is lifted off the revolving disc n by means of the ejector o.

The finishing of the spring ring is effected by a separate device or by hand in that, after the soldering on of the suspension eye, the catch spring and the catch are inserted and then the walls of the slot i returned into their parallel position by compressing the guide sleeve 2'.

I claim 1. A process for working guide sleeves for spring rings, consisting in cutting the slot, in which the shank of the catch button runs, by means of a cutter, and in finishing said slot by means of a similar tool the cutting edge of which moves in opposite direction.

2. A process as specified in claim 1, consisting in removing cut faces visible from the outer side formed by the cutting of the slot and the burr-like sharp edges formed on the edges of said faces by means of tapered end mills, and in producing at the same time a funnel-shaped opening for inserting the catch spring and the catch.

In testimony whereof I aflix my signature.

BERNHARD FOERSTER. Y 

